Priority API Integration Skill

Source of Truth Hierarchy (CRITICAL)

Data Type	Source of Truth	Why
Device USAGE	LOCAL DB	Real-time, safety-critical
Device METADATA	ERP	Inventory management
Patient Treatment Records	LOCAL DB	Direct observation
Inventory Counts	ERP	Business operations

Golden Rule: LOCAL DB wins for SAFETY. ERP wins for INVENTORY.

Applicator Validation Pattern

typescript

// 1. CHECK LOCAL DB FIRST (Safety)
const localUsage = await db.ApplicatorUsage.findOne({ where: { serialNumber } });
if (localUsage) {
  throw new Error(`SAFETY CRITICAL: Already used on ${localUsage.usedAt}`);
}

// 2. CHECK ERP (Inventory metadata)
let erpData = await priorityService.getApplicator(serialNumber);

// 3. FAIL-CLOSED if ERP offline
if (!erpData) {
  const cached = await db.ApplicatorCache.findOne({ where: { serialNumber } });
  if (!cached || isCacheStale(cached, 24)) {
    throw new Error('SAFETY BLOCK: Cannot verify - ERP offline');
  }
  erpData = cached;
}

// 4. VALIDATE metadata
if (erpData.SIBD_NOUSE === 'Y') throw new Error('Marked NO USE');
if (new Date(erpData.SIBD_EXPIRY) < new Date()) throw new Error('Expired');

OData Query Standards

Field Selection (MANDATORY)

typescript

// CORRECT
const query = {
  $select: 'ORDNAME,CUSTNAME,SIBD_TREATDAY,SIBD_SEEDQTY',
  $filter: `SIBD_TREATDAY ge datetime'${date}'`,
  $top: 100
};

// WRONG - Never use wildcards
const query = { $select: '*' };

Pagination

•DEFAULT: 100 records per page
•MAXIMUM: 500 records (site lists)
•Use $top and $skip for server-side paging

Retry Pattern

•MAX ATTEMPTS: 4
•INITIAL DELAY: 200ms
•MULTIPLIER: 2.0x
•JITTER: 10%

Transient Errors (RETRY)

408, 429, 500-504, ECONNRESET, ETIMEDOUT

Non-Transient Errors (FAIL)

400, 401, 403, 404

Circuit Breaker

•OPEN after 5 consecutive failures
•HALF_OPEN after 60 seconds
•Test single request before closing

ApplicatorCache Usage

The ApplicatorCache model stores ERP metadata for offline resilience:

typescript

// Update cache on every successful ERP query
await ApplicatorCache.upsert({
  serialNumber,
  SIBD_NOUSE: erpData.SIBD_NOUSE,
  SIBD_EXPIRY: erpData.SIBD_EXPIRY,
  SIBD_TREATTYPE: erpData.SIBD_TREATTYPE,
  cachedAt: new Date()
});

// Check cache age (24h TTL)
const CACHE_TTL_MS = 24 * 60 * 60 * 1000;
const isStale = (Date.now() - cache.cachedAt.getTime()) > CACHE_TTL_MS;

Pre-Integration Checklist

• Local DB checked BEFORE ERP for usage validation
• ERP offline = BLOCK (fail-safe), not proceed with warning
• $select specifies exact fields (no wildcards)
• Retry logic with exponential backoff
• Cache updated on every successful ERP query